acgi

test.php

<?php

$userCurrentCommittees = array(); // from drupal user
$agciUpdatedCommittees = array(); // from acgi

$committeesToRemove = $userCurrentCommittees;

foreach ($agciUpdatedCommittees as $committee){
  // * run_update_committee_method
  if (in_array($committee, $userCurrentCommittees)) {
    // * remove $committee from $committeesToRemove
  }
}

foreach ($committeesToRemove as $committee) {
  // * remove committee from user / field collection
}